Understand harvest? (6)
I believe the answer is:
gather
This clue is a double definition.
'understand' is the first definition.
(synonyms)
'harvest?' is the second definition.
(I know that harvest is a more specific form of gather)
(Other definitions for gather that I've seen before include "Assemble; understand" , "Come together for the rag" , "put in pleats" , "Assemble - conclude - contract" , "From information given, learn" .)